An antenna of a base station is used to transform radio frequency signals into electromagnetic wave signals, and radiate the electromagnetic wave signals to the space; or receive electromagnetic wave signals transmitted from a terminal, transform the electromagnetic wave signals into radio frequency signals and deliver the radio frequency signals to the base station.
Each antenna controls a certain range of area, and the area is referred to as a sector or a cell. Electromagnetic waves are radiated or received in the area, and a radiation radius is controlled by using a method for controlling a tilt angle of a main lobe. The larger the tilt angle of the main lobe is, the smaller the radiation radius is. The sector coverage area of the cell is controlled by controlling the horizontal direction of the main lobe of the antenna.
The following are several manners to tilt the main lobe:
1. Install the antenna in a tilt status. The formed direction of the main lobe, also known as the tilt angle, has already been fixed in design, which is referred to as fixed electrical tilt (FET, Fixed Electrical Tilt). The tilt angle cannot be changed unless an operator climbs up the tower of the base station to adjust or change an installation support.
2. Dispose a phase shifter inside the antenna, so that the antenna becomes a manual electrical tilt (MET, Manual Electrical Tilt) antenna. When the tilt angle needs to be changed, an operator needs to climb up the tower to adjust the phase shifter, which is also quite inconvenient.
3. Add a motor device on the basis of the antenna in the manner 2, being used for remote control. The antenna of the base station is referred to as a remote electrical tilt (RET, Remote Electrical Tilt) antenna. The hardware increases costs. Besides, the electrical tilt in such manner cannot be separately configured according to different carrier waves and different channels, so the flexibility is limited.
A multi-beam antenna refers to that the excitation for an antenna array is weighted by amplitude and a phase with a certain relationship, making the antenna direct to different directions to form multiple narrow beams. By adjusting the vertical characteristic of the beams, the antenna obtains good side lobe suppression and a desirable tilt angle in the vertical direction. In the same sector, a multi-beam antenna may be applied to make received signals the strongest by determining to select different corresponding beams. In addition, the multi-beam antenna may be used as a sector splitter to split a sector into two sectors, so that an overlapping area between the two sectors is smaller, which is conducive to reduce soft handover and softer handover, and increase the system capacity to enhance capacity.
The existing multi-beam antenna with an adjustable tilt angle is connected to a transceiver (Transceiver, TRX for short) module through a feeder line. In the connection, transmission loss exists. Besides, a discrete component increases the equipment costs, and also increases the labor costs of maintenance.